Influence of JAK2V617F allele burden on clinical phenotype of polycythemia vera patients: A study from India

BACKGROUND: Elevated JAK2V617F allele burden is associated with enhanced expression of downstream target genes in Philadelphia negative chronic myeloproliferative neoplasms (CMPNs) which include PV, ET & PMF. Previous studies have shown the impact of JAK2V617F allele burden on clinical phenotype of CMPNs. However, there is no data from India regarding the association between JAK2V617F allele burden and clinical phenotype in PV. AIMS/SETTINGS AND DESIGN: We aimed to investigate the effect of allele burden on clinical phenotype in 90 JAK2V617F positive PV patients and to see its influence on disease related complications. MATERIAL AND METHODS: Allele burden of 90 JAK2V617F positive PV patients was quantified by Real-time polymerase chain reaction (RQ-PCR). RESULTS: 74/90 (82.22%) were males and 16/90 (17.78%) were females (median 45 years, range 35-78). Patients with age >50 years had significantly higher JAK2V617F allele burden (median 40.15%, range 0.49–91.62 %) than patients with ≤ 50 years age (median 48.59 %, range 0.56–86.74 %; P < 0.032). Patients with splenomegaly had significantly higher JAK2V617F allele burden (mean 50.24%, range 6.91–84.17%) than patients without splenomegaly (mean 33.82 %, range 0.49–71.83 %; P < 0.017). Patients with higher allele burden (median 57.20, range 43.4–72.03%) had significantly raised thrombotic events than the patients with lower allele burden (median 37.38, range 0.49–84.17%; P < 0.043). 49/90 (54%) were homozygous and 41/90 (46%) were heterozygous. CONCLUSIONS: Higher JAK2V617F allele burden showed association with increased age, splenomegaly and thrombotic events. Thus, it may be considered for prognostication and setting up the treatment protocol in PV patients.